Vehicle roof frame component and integrated blank for vehicle roof frame component

Abstract

The present invention addresses the problem of shortening the manufacturing process for increasingly complex roof frame components, and an objective thereof is to obtain a roof frame component by integral molding (integral press molding).　According to the present invention, a vehicle roof frame component can be obtained by press molding an integrated blank having two roof rail inners that extend in the direction of travel of the vehicle, one or more roof crosses connected to the two roof rail inners, and joint portions where blanks corresponding to the roof rail inners and blanks corresponding to the roof crosses are joined at overlapping portions where the blanks overlap each other.

Description

Vehicle roof frame part and integrated blank for vehicle roof frame part

[0001] The present invention relates to a vehicle roof frame part and an integrated blank for a vehicle roof frame part.

[0002] In particular, with a focus on automobiles, there is a demand to reduce the life cycle GHG (total emissions of greenhouse gases throughout the life cycle), and the demand for integration of parts and modules aimed at increasing the efficiency of the manufacturing line by reducing the number of parts and omitting processes is increasing. In particular, if large parts, such as vehicle frame parts, for example, door rings and roofs of automobiles, which are combinations of a large number of members and parts, can be integrally formed (integrally press-formed), the effect will be extremely large. Therefore, there is an increasing demand for integrally press-forming frame parts using a blank that combines different types of steel sheets, so-called tailor-welded blanks (TWB: Tailor Welded Blank).

[0003] As an example of integrally forming a vehicle frame member, integrally forming a side frame part (door ring) for an automobile by TWB has been proposed (for example, Patent Document 1). Since the strength and plate thickness requirements for each part of an automobile door ring are different, different types of steel sheets (blanks) are combined and manufactured, so the effect of process omission by integrally forming it by TWB is large.

[0004] On the other hand, in the skeletal parts (roof frame parts) around the roof of a vehicle, a plurality of roof cross members that connect the side frame parts on both sides are arranged and configured. For the roof frame parts, the strength and plate thickness requirements are different for each roof cross member, and like the side frame parts, they are manufactured by combining different types of steel sheets (blanks). However, when actually assembling an automobile, first, the side frame parts (door rings) on both sides are assembled, and then the roof cross members are attached one by one to connect them. Therefore, it takes time to manufacture and attach the roof cross members, and shortening the attachment time of the roof frame parts is required.

[0005] International Publication No. 2020 / 002335

[0006] As vehicle safety becomes an increasingly important factor, there is a demand for improved impact resistance of roof frames to ensure sufficient interior space during side collisions and rollovers. Furthermore, the increasing diversity of vehicle designs, such as sunroofs, and the demand for lighter vehicle weights are complicating the construction of roof frames. Consequently, the manufacturing process for roof frames is also becoming more complex, leading to increased manufacturing costs, and there is a growing need for simplification of the manufacturing process and cost reduction.

[0007] The present invention aims to shorten the manufacturing process of increasingly complex roof frame components and to obtain roof frame components by integral molding (integral press molding).

[0008] To achieve the above objectives, the inventors diligently developed a vehicle roof frame component based on an automobile roof frame, incorporating the perspective of shortening the manufacturing process through integral molding. Specifically, instead of joining each roof cloth to the door ring one by one, they focused on integrally molding a roof frame component with the roof cloth already arranged. As a result, they obtained the following findings.

[0009] (a) We focused on the fact that in automobile assembly work, the roof cloth is joined to the roof rail inner of the door ring (a part of the roof rail that is located on the inside of the vehicle). Therefore, we conceived of positioning the roof rail inner as a part of the roof frame component and proceeded with development by integrally molding the roof rail inner on both sides with the roof cloth.

[0010] (i) The roof rail inners and roof cross on both sides are not formed from a single type of blank (steel material), but are often composed of multiple blanks. Therefore, we have found that an integrated blank can be manufactured by joining the blanks corresponding to the roof rail inner and roof cross in advance to create a TWB (Tower Wide Beam).

[0011] (c) The obtained integrated blank can be press-formed to obtain the desired roof frame component in a single press-forming operation. Since high-tensile steel is often used as the blank, hot stamping is desirable for the press-forming method, and it has been found that conventional hot stamping methods can also be applied.

[0012] (e) We found that by using an overlapping joint between the roof rail inner and the roof cloth, the thickness of the plate at the joint increases, thus maintaining the rigidity of the conventional roof rail inner. As a result, it is possible to obtain an integrally molded roof frame component without reducing the strength of the door ring (side frame).

[0013] (O) Furthermore, we found that the rigidity of the joint can be increased by press molding to form a bead at the joint between the roof rail inner and the roof cloth.

[0014] This invention is based on the above findings, and its purpose is as follows.

[0015] [1] A vehicle roof frame component comprising a plurality of steel plates joined together, wherein the roof frame component has two roof rail inners extending in the direction of vehicle travel, and one or more roof crosses connected to the two roof rail inners, and the blanks corresponding to the roof rail inners and the blanks corresponding to the roof crosses have a joint where they are joined at overlapping portions. [2] The vehicle roof frame component according to [1], wherein the joint is located in the overlapping portion of the joint where at least one of the roof rail inners and at least one of the roof crosses are connected. That is, a vehicle roof frame component comprising a plurality of steel plates joined together, wherein the roof frame component has two roof rail inners extending in the direction of vehicle travel, and one or more roof crosses connected to the two roof rail inners, and in a connection portion where at least one of the roof rail inners and at least one of the roof crosses are connected, the blank corresponding to the roof rail inner and the blank corresponding to the roof cross are joined by an overlapping portion that is superimposed on each other. Typically, the connection portion is a region enclosed by a virtual line indicating the width of the roof rail inner and a virtual line indicating the width of the roof cross, and at least a part of the overlapping portion is located inside the connection portion, as described in [2] above. [3] The roof cloth comprises a top plate portion extending in the longitudinal direction of the roof cloth and at least one vertical wall portion adjacent to the top plate portion, the roof rail inner comprises a top plate portion extending in the longitudinal direction of the roof rail inner and at least one vertical wall portion adjacent to the top plate portion, and the connecting portion is the vehicle roof frame component according to [1] or [2], wherein the roof cloth is connected to the vertical wall portion of the roof rail inner so as to abut against it. [4] The overlapping portion is the vehicle roof frame component according to [3], wherein at least the top plate portion of the roof rail inner is located.[5] A vehicle roof frame component according to any one of items [1] to [4], wherein the roof cloth has a bead that passes through the overlapping portion and extends in the longitudinal direction of the roof cloth. [6] A vehicle roof frame component according to any one of items [1] to [5], wherein the roof rail inner has a bead that passes through the overlapping portion and extends in the longitudinal direction of the roof rail inner. [7] A vehicle roof frame component according to any one of items [1] to [6], wherein the roof frame component is a hot-stamped component. [8] A vehicle roof frame component according to any one of items [1] to [7], wherein at least one of the joints is a joint without a HAZ softening portion. [9] The joint without a HAZ softened portion is a vehicle roof frame component as described in [8] above, wherein, in a cross section perpendicular to the surface of the outermost blank including the center of the joint, at a position 3 / 4 of the plate thickness from the surface of the outermost blank, when the Vickers hardness at a position that is not joined and is 15 mm or more away from the center of the joint is Hvm, the difference between the maximum and minimum Vickers hardness in a range within 5 mm toward the base material from the end of the weld metal of the joint is 0.2 Hvm or less (preferably ΔHv is 0.1 Hvm or less) (i.e., there is no HAZ softened portion).

[10] The roof cloth comprises a top plate portion extending in the longitudinal direction of the roof cloth and at least one vertical wall portion adjacent to the top plate portion, the roof rail inner comprises a top plate portion extending in the longitudinal direction of the roof rail inner and at least one vertical wall portion adjacent to the top plate portion, the joint portion without HAZ softening portion is present on one or both of the top plate portion of the roof rail inner and the top plate portion of the roof cloth, the vehicle roof frame component described in [8] or [9]

[11] A press-formed integrated blank configured as a joint structure of multiple steel plates for a vehicle roof frame component constituting the roof of a vehicle, the roof frame component comprises two roof rail inners extending in the direction of vehicle travel and one or more roof cloths connected to the two roof rail inners, the integrated blank comprises two blanks corresponding to roof rail inners extending in the direction of vehicle travel and one or more blanks corresponding to roof cloths connected to the two blanks corresponding to roof rail inners, An integrated blank for a vehicle roof frame component, characterized in that at least one blank corresponding to the roof rail inner and at least one blank corresponding to the roof cloth have a joint joined by overlapping portions. Typically, the integrated blank for a vehicle roof frame component according to

[11] is arranged in a region enclosed by a virtual line indicating the width of the blank corresponding to the roof rail inner and a virtual line indicating the width of the blank corresponding to the roof cloth, wherein at least a portion of the overlapping portion is arranged in a region enclosed by a virtual line indicating the width of the blank corresponding to the roof rail inner and the roof cloth.

[12] The integrated blank for a vehicle roof frame component according to

[11] is arranged in a region enclosed by overlapping portions, wherein the blank corresponding to the roof cloth has at least one top plate portion extending in the longitudinal direction of the blank corresponding to the roof cloth and one vertical wall portion adjacent to the top plate portion, the blank corresponding to the roof rail inner has at least one top plate portion extending in the longitudinal direction of the blank corresponding to the roof rail inner and one vertical wall portion adjacent to the top plate portion, and the overlapping portion is arranged in at least the portion corresponding to the top plate portion of the blank corresponding to the roof rail inner.

[13] The integrated blank for a vehicle roof frame component according to

[11] or

[12] , wherein the joint is a joint formed by resistance spot welding, laser spot welding, or overlap welding.

[14] The integrated blank for a vehicle roof frame component according to any one of

[11] to

[13] , wherein the joint is located in at least one of the portion corresponding to the top plate portion of the blank corresponding to the roof rail inner and the portion corresponding to the top plate portion of the blank corresponding to the roof cloth.

[0016] According to the present invention, a vehicle roof frame component can be obtained by integrally molding an integrated blank (TWB) formed by joining multiple partial blanks, thereby drastically shortening the manufacturing process for the roof frame component.

[0017] Figure 2 is divided into Figure 2-1 and Figure 2-2, but these are combined to form Figure 2. This is a schematic diagram illustrating an embodiment of the present invention of an automobile roof frame. Figure 1(a) is a schematic diagram showing an example of an automobile frame. Figure 1(b) is a schematic diagram of a roof frame component according to an embodiment of the present invention. This is a schematic diagram illustrating an example of the roof frame component of Figure 1(b) and its integrated blank according to the present invention. Figure 2(a) is a schematic diagram showing an example of the roof frame component of Figure 1(b) and the integrated blank constituting the roof frame component superimposed. Figure 2(b) is a schematic diagram showing the integrated blank of Figure 2(a). This is a schematic diagram for illustrating the form of the overlapping portion of the roof rail inner equivalent blank and the roof cloth equivalent blank. Figure 2(c) is a schematic diagram showing the roof frame component of Figure 2(a). This is a schematic diagram for illustrating the connection portion and overlapping portion of the roof rail inner and roof cloth. This is a schematic diagram illustrating the connection portion of the roof rail inner and roof cloth. Figure 3(a) is a schematic diagram of the connection portion when integrally molded according to an embodiment of the present invention. Figure 3(b) is a schematic diagram of the connection between a conventional roof rail inner and roof cloth. Figure 4 is a schematic diagram illustrating an example of the joining state at the connection between the roof rail inner and roof cloth. Figure 4(a) shows an example of the connection as a roof frame component after press forming, and Figure 4(b) is a schematic diagram showing an example of an integrated blank of that connection. Note that Figure 4(a) is a view from the inside of the vehicle. This is a schematic diagram illustrating beads provided on the roof cloth. Figure 5(a) is a schematic diagram illustrating two rows of beads formed on the top plate portion of the roof cloth. Figure 5(b) is a schematic diagram illustrating a cross-section in the longitudinal direction of the roof cloth at the bead formation portion. Note that Figure 5(a) is a view from the inside of the vehicle, and in Figure 5(b), the bottom of the drawing is in the direction of the outside of the vehicle. This is a schematic diagram illustrating beads provided on the roof cloth that pass through the roof rail inner. Figure 6(a) is a schematic diagram illustrating two rows of beads formed on the top plate portion of the roof cloth. Figure 6(b) is a schematic diagram illustrating a cross-section of the bead-forming portion in the longitudinal direction of the roof cloth. Note that Figure 6(a) is a view from the inside of the vehicle, while in Figure 6(b), the bottom of the drawing is in the direction of the outside of the vehicle.This is a schematic diagram illustrating a case where beads are formed in combination on the roof cloth and the roof rail inner. Figure 7(a) is a schematic diagram illustrating a case where two rows of beads are formed on the top plate portion of the roof cloth and one row of beads is formed on the top plate portion of the roof rail inner. Figure 7(b) is a schematic diagram illustrating a cross-section in the longitudinal direction of the roof cloth where the beads are formed. Note that Figure 7(a) is a view from the inside of the vehicle, and in Figure 7(b), the bottom of the drawing is in the direction of the outside of the vehicle. This is a diagram for explaining the manufacturing process of a part by press forming of a TWB (integrated blank) according to an embodiment of the present invention. This is a diagram for explaining the HAZ softening part by spot welding.

[0018] This embodiment will be described using an example of an automobile roof frame, which is one embodiment (hereinafter simply referred to as "this embodiment") of a vehicle roof frame component that constitutes the roof portion of a vehicle according to the present invention. Figure 1 shows an overview of an automobile frame 100. Figure 1(a) shows an overview of a general automobile frame 100, and Figure 1(b) shows an overview of a roof frame component 101 that imitates it as an embodiment. In Figure 1, the direction of the white arrow in the drawing is the direction of vehicle travel.

[0019] The roof frame component 101 according to this embodiment is a component that constitutes the roof portion (upper surface (top plate portion)) of an automobile vehicle, and is composed of two roof rail inners 11 extending in the direction of vehicle travel and one or more (three in Figure 1(b)) roof crosses 12 connected to these two roof rail inners 11. The number of roof crosses 12 is not particularly limited, and one or more are sufficient, but it is preferable to have two or more for the structure of the automobile.

[0020] The roof rail inners 11 extend in the direction of vehicle travel and are arranged in parallel, spaced apart in the vehicle width direction (perpendicular to the direction of vehicle travel), defining the width of the vehicle. The roof cross 12 is connected so as to connect these two roof rail inners 11 and so as to abut against the roof rail inners 11. The part where the roof cross 12 connects to the roof rail inners 11 is called the connection part.

[0021] The shape of the roof rail inner 11 is not particularly limited. Typically, the roof rail inner 11 has a top plate portion extending in the longitudinal direction and at least one vertical wall portion adjacent to the top plate portion. That is, the cross-sectional shape of the roof rail inner 11 in a cross section perpendicular to the longitudinal direction (hereinafter, the cross-sectional shape in a cross section perpendicular to the longitudinal direction is simply referred to as the cross-sectional shape) is often a hat shape, C shape, L shape, etc. The cross-sectional shape of the roof rail inner in this embodiment is based on an L shape with one vertical wall portion adjacent to the top plate portion, and flange portions are arranged on the top plate portion and the vertical wall portion. Therefore, it is composed of a flange portion, a top plate portion, a vertical wall portion, and a flange portion in that order.

[0022] The shape of the roof cloth 12 is not particularly limited. Typically, the roof cloth 12 has a top plate portion extending in the longitudinal direction and at least one vertical wall portion adjacent to the top plate portion. That is, the cross-sectional shape of the roof cloth 12 is often a hat shape, C shape, L shape, etc. The cross-sectional shape of the roof cloth 12 in this embodiment has two vertical wall portions adjacent to the top plate portion, and flange portions are arranged on both vertical wall portions, resulting in a so-called hat-shaped structure. Therefore, it is composed of a flange portion, a vertical wall portion, a top plate portion, a vertical wall portion, and a flange portion in that order.

[0023] The roof cross 12 is connected so as to connect the two roof rail inners 11 and so as to abut against the roof rail inners 11, but typically the roof cross 12 is connected so as to abut against the vertical wall portion of the roof rail inners 11.

[0024] In this embodiment, a roof rail inner 11 is used, but it does not have to be the roof rail inner 11 itself; for example, a roof rail inner-like component may be used. This is because when assembling the automobile, the roof rail inner-like component can be attached to the roof rail inner of the door ring, allowing the automobile to be assembled. This embodiment is an example in which a roof rail inner is used, and this embodiment will be explained using this example.

[0025] In conventional automobile frame structures, the roof rail inner is included in the side frame component (door ring), and during automobile assembly, after assembling the door rings on both sides in the width direction of the automobile, the roof cloth is joined one by one to the roof rail inner, which is a part of the door ring (for example, by spot welding). In the roof frame component according to this embodiment, the roof rail inner is positioned as a part (a single component) of the roof frame component, making it possible to integrally mold the roof rail inner on both sides and the roof cloth.

[0026] Figure 2(b) shows a schematic diagram of the integrated blank 201 for a vehicle roof frame component according to this embodiment. The roof rail inner 11 and roof cross 12 on both sides are not formed from a single type of steel plate (blank), but are often constructed as a joined structure of multiple steel plates (blanks). Therefore, the integrated blank 201 can be manufactured by joining blanks corresponding to the roof rail inner 11 and roof cross 12 in advance to create a two-wheel blank (TWB).

[0027] The integrated blank according to this embodiment corresponds to the roof frame component according to this embodiment. That is, the integrated blank according to this embodiment has two blanks corresponding to roof rail inners that extend in the direction of vehicle travel, and one or more blanks corresponding to roof crosses that are connected to the two blanks corresponding to roof rail inners, and at least one of the blanks corresponding to roof rail inners and at least one of the blanks corresponding to roof crosses have a joint that is joined by overlapping portions that are superimposed on each other, making it an integrated blank for a vehicle roof frame component.

[0028] Figure 2(a) shows a schematic diagram overlaying an example of an integrated blank and a molded roof frame component, separated into blanks that constitute the roof frame component shown in Figure 1(b). In the example in Figure 2(a), the integrated blank 201 for the vehicle roof frame component is composed of two blanks corresponding to roof rail inners 11 (roof rail inner equivalent blanks 21) and three blanks corresponding to roof crosses 12 (roof cross equivalent blanks 22). Within a single roof rail inner equivalent blank 21, multiple different steel plates (blanks) can be joined to form the roof rail inner equivalent blank 21. The strength and thickness of the steel plates to be used can be determined as needed based on the structural design of the automobile.

[0029] Similarly, within a single roof cross equivalent blank 22, multiple different steel plates (blanks) can be joined together to form the roof cross equivalent blank 22, and the strength and thickness of the steel plates to be used can be determined by the structural design. Also, although three roof cross equivalent blanks 22 can be seen in Figure 2(a), the type of steel plate may differ in each roof cross equivalent blank 22, and this can also be determined as needed in the structural design.

[0030] In manufacturing the integrated blank 201, the usual TWB manufacturing method can be applied. However, from the viewpoint of ensuring the strength and rigidity of the part where the roof rail inner 11 and the roof cloth 12 are connected, it is preferable to overlap and join the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 at the connection part 31 between the roof rail inner 11 and the roof cloth 12. Here, the overlapping part of these two blanks is called the overlapping part 41, and the joined part (for example, the welded part) is called the joint part 51.

[0031] The connection portion 31 between the roof cloth 12 and the roof rail inner 11 is the region in the roof frame component 101 enclosed by a virtual line 311 indicating the width of the roof rail inner 11 and a virtual line 312 indicating the width of the roof cloth 12, as shown in Figure 2(c).

[0032] Figure 2(c) shows the roof frame component 101 shown in Figure 2(a). In Figure 2(c), the area enclosed by the imaginary line 311 indicating the width of the roof rail inner 11 and the imaginary line 312 indicating the width of the roof cross 12 is the connection portion 31. For the sake of explanation, only the connection portion 31 relating to the lower roof rail inner 11 of the roof frame component 101 in Figure 2(c) is shown. The upper roof rail inner 11 also has a similar connection portion, but to avoid overlapping with the display of the overlapping portion, only the connection portion of the lower roof rail inner 11 is shown.

[0033] As can be seen from Figure 2(c), the imaginary line 311 indicating the width of the roof rail inner 11 is a line indicating the outer edge (end face) of the roof rail inner 11 in the direction perpendicular to the longitudinal direction (width direction). If the line indicating the end face is interrupted, the lines indicating the end face before and after the interruption are extended or supplemented to draw a smoothly continuous imaginary line. For example, when the roof rail inner 11 is viewed in a cross section perpendicular to the longitudinal direction, if it has a hat-shaped cross section (a shape with a top plate in the center, vertical walls on both sides of it, and flanges on both sides of the vertical walls), the lines corresponding to the outer edges of both flanges become the imaginary line 311 indicating the width of the roof rail inner 11. For example, if the roof rail inner 11 has a U-shaped cross section (a shape with a top plate in the center, and vertical walls on both sides of it), the lines corresponding to the outer edges of both vertical walls become the imaginary line 311 indicating the width. In parts where the flange or vertical wall is interrupted, the outer edges of the flange or vertical wall before and after the interruption are smoothly extended or supplemented to draw the imaginary line.

[0034] As can also be seen from Figure 2(c), the imaginary line 312 indicating the width of the roof cloth 12 is defined as a line drawn perpendicular to the longitudinal direction of the roof rail inner 11 from the intersection of the outer edge (end face) of the roof cloth 12 in the direction perpendicular to the longitudinal direction (width direction) and the imaginary line 311 indicating the width of the roof rail inner 11 (i.e., the intersection of the end face (outer edge) in the width direction of the roof cloth 12 after pressing and the end face (outer edge) in the width direction of the roof rail inner 11). In the example in Figure 2(c), at the point where the roof cloth 12 connects to the roof rail inner 11, the width of the roof cloth 12 gradually increases as it connects to the roof rail inner 11. Therefore, the outer edge of the roof cloth 12 in the width direction also spreads outward and intersects with the imaginary line 311 of the roof rail inner 11, so the spacing of the imaginary lines 312 of the roof cloth 12 is wider than the width of the middle part of the roof cloth 12.

[0035] The overlapping portion 41 is the part where the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 are superimposed. Since both blanks are press-formed while superimposed, the overlapping portion 41 of both blanks remains in the roof frame part after press-forming. Figure 2(c) shows the overlapping portion 41 in the roof frame part 101, which is the part where the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 are superimposed. As mentioned above, for the sake of explanation, the overlapping portion 41 relating to the upper roof rail inner 11 of the roof frame part 101 in Figure 2(c) is shown.

[0036] The overlapping portion 41 is positioned at least partially inside the connecting portion 31. In the conceptual diagram of Figure 2(c), parts of the two overlapping portions 41 at the front of the vehicle (left side of the drawing) are positioned to overlap the entire connecting portion 31. It is desirable that the proportion of the connecting portion 31 over which the overlapping portion 41 covers is as large as possible. Preferably, the overlapping portion 41 covers 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% of the connecting portion 31. The overlapping portion 41 is often T-shaped, as in the left and center roof cross 12 and roof rail inner 11 in Figure 2(c), but it can also be L-shaped, as in the right roof cross 12 and roof rail inner 11 in Figure 2(c).

[0037] The method of overlapping the roof rail inner equivalent blank 21 and the roof cross equivalent blank 22 at the overlapping portion 41 of the two blanks is not particularly limited. Figure 2(b) shows an integrated blank of the roof frame component shown in Figure 2(a). Figure 2(b) is a schematic diagram showing an example of how the roof rail inner equivalent blank 21 and the roof cross equivalent blank 22 are overlapped in an example of an integrated blank 201. For example, in Figure 2(b), at the overlapping portion 41 of the upper roof rail inner equivalent blank and the leftmost of the three roof cross equivalent blanks 22, the roof cross equivalent blank 22 has a portion that protrudes on one side of its end toward the longitudinal direction of the roof rail inner equivalent blank 21, and the roof rail inner equivalent blank 21 has a portion that protrudes toward the roof cross equivalent blank 22, thus forming an L-shaped overlapping portion 41. Furthermore, the upper overlapping portion 41 of the middle roof cloth equivalent blank 22 forms an overlapping portion 41 in which the roof cloth equivalent blank 22 has portions that protrude on the longitudinal side of the roof rail inner equivalent blank 21 on both sides of its end. The upper overlapping portion 41 of the rightmost roof cloth equivalent blank 22 forms an overlapping portion 41 in which only one side of the end of the roof cloth equivalent blank 22 has a portion that protrudes onto the roof rail inner equivalent blank 21. These may be combined to form an overlapping portion 41. For example, as with the lower overlapping portion 41 of the middle roof cloth equivalent blank 22, the roof rail inner equivalent blank 21 may have a portion that protrudes towards the roof cloth equivalent blank 22, and the roof cloth equivalent blank 22 may have portions that protrude on the longitudinal side of the roof rail inner equivalent blank 21 on both sides of its end, forming a T-shaped overlapping portion 41.

[0038] Furthermore, in the example shown in Figure 2(b), the overlapping portions 41 on both sides of the right and left roof cross equivalent blanks 22 (the overlapping portions with the two roof rail inner equivalent blanks 21) are almost identical in shape. However, as with the middle roof cross, the overlapping portions 41 at both ends may have different shapes.

[0039] In either case, it is preferable to join the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 at the overlapping portion 41. That is, the joint (the part where the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 are joined by welding or the like) will be located within the overlapping portion 41.

[0040] By joining the overlapping portion 41 of the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 and integrally molding (press molding) them, the shapes of both can be aligned during press molding. Figure 3(a) shows an overview of the connection portion 31 when the overlapping portion 41 is integrally molded. Figure 3(b) shows an overview of the connection portion 31 of a conventional roof rail inner 11 and roof cloth 12. Conventionally, the roof rail inner 11 and the roof cloth 12 were manufactured separately and joined together, so the top plate portion 111, vertical wall portion 112, and flange portion 113 of the roof rail inner were continuous, and thus had a certain rigidity against bending moments transmitted from the roof cloth 12. However, as shown in Figure 3(a), when integrally molded, the vertical wall portion 112 and flange portion 113 of the roof rail inner become discontinuous as if they were separated at the connection portion, and an opening is formed in the vertical wall portion of the roof rail inner 11. As a result, the bending rigidity of the roof rail inner 11 against bending received from the roof cloth 12 is weakened. Therefore, by overlapping and joining the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22 at the connection point, the thickness of the connection point 31 can be increased, compensating for the discontinuity of the vertical wall portion 112 and flange portion 113 of the roof rail inner and ensuring rigidity.

[0041] Since the roof cloth 12 is usually a hat-shaped cross section (a structure having a top plate portion 121 and vertical wall portions 122 on both sides, and flange portions 123 on both sides thereafter) or a C-shaped cross section (a structure having a top plate portion and vertical wall portions on both sides), it is preferable to place at least the overlapping portion 41 on the top plate portion 111 of the roof rail inner. In that case, it is preferable to place at least the joint portion 51 of the overlapping portion 41 on the top plate portion 111 of the roof rail inner. This is because the top plate portion does not undergo complex bending during press forming, and the material flow behavior is simple, so less load is placed on the joint portion (welded portion). The portion of the overlapping portion other than the top plate portion 111 of the roof rail inner may be joined after forming (press forming). By joining after forming, the joint portion is not affected by the stress and strain generated by the complex material flow behavior during press forming, so cracking can be suppressed.

[0042] Figure 4 shows an example of the joining state at the connection between the roof rail inner and the roof cloth. Figure 4(a) shows an example of the connection as a roof frame component after press molding, and Figure 4(b) shows an example of the integrated blank of the connection. Figure 4(a) is a view from the inside of the vehicle. The roof cloth 12 illustrated in Figure 4(a) has a hat-shaped cross section (a structure having a top plate portion 121 and vertical wall portions 122 on both sides of it, and flange portions 123 on both sides of those), and the roof rail inner 11 has a top plate portion 111 and a vertical wall portion 112 adjacent to one side, and flange portions 113 on the other side of the top plate portion 111 and on the vertical wall portion 112, resulting in a cross-sectional shape that resembles overlapping L-shaped cross sections.

[0043] When joining the roof rail inner and the roof cloth, it is preferable to join them at the overlapping portion of the top plate portion 111 of the roof rail inner and the top plate portion 121 of the roof cloth, as shown in Figure 4(a). In other words, the joining portion 51 will be located at the overlapping portion of the top plate portion 111 of the roof rail inner and the top plate portion 121 of the roof cloth.

[0044] Figure 4(b) is an integrated blank for obtaining the connection part of Figure 4(a). In the example of Figure 4(b), the blank 21 corresponding to the inner roof rail consists of a portion corresponding to the top plate part of the inner roof rail (top plate part corresponding portion) 211, a portion corresponding to the vertical wall part (vertical wall part corresponding portion) 212, and a portion corresponding to the flange part (flange part corresponding portion) 213. Similarly, the blank 22 corresponding to the roof cross (the portion surrounded by the thick line in Figure 4(b)) consists of a portion corresponding to the top plate part of the roof cross (top plate part corresponding portion) 221, a portion corresponding to the vertical wall part (vertical wall part corresponding portion) 222, and a portion corresponding to the flange part (flange part corresponding portion) 223. In the integrated blank, as shown in Figure 4(b), in the overlapping part 41 of the blank 21 corresponding to the inner roof rail and the blank 22 corresponding to the roof cross, the joining part 51 may be arranged at least on one of the top plate part corresponding portion 211 of the blank corresponding to the inner roof rail and the top plate part corresponding portion 221 of the blank corresponding to the roof cross. Preferably, the joining part may be arranged at least on one of the top plate part corresponding portion 211 of the inner roof rail and the top plate part corresponding portion 221 of the blank corresponding to the roof cross in the overlapping part 41 of both blanks 21 and 22. More preferably, at least in the portion corresponding to the connection part in the parts after press forming, it may have a joining part joined at the overlapping part 41 of both blanks 21 and 22. In the example of Figure 4(b), in the overlapping part 41 of both blanks 21 and 22, the joining part may be arranged at least on the top plate part corresponding portion 211 of the inner roof rail. In Figure 4(b), an example is shown in which three joining parts 51 (black dots) are arranged on the top plate part corresponding portion 211 of the blank corresponding to the inner roof rail and five joining parts 51 are arranged on the top plate part corresponding portion 221 of the blank corresponding to the roof cross (in Figure 4(b), for the sake of clarity, the reference lines are drawn only at one place). The number and arrangement of the joining parts 51 are not particularly limited. They may be appropriately determined from the viewpoints of component strength design, weldability, workability, productivity, etc.

[0045] Regarding the overlapping portion 41 of the roof rail inner equivalent blank 21 and the roof cloth equivalent blank 22, when the roof cloth portion takes on a hat-shaped cross section, it is preferable to overlap them so that the roof cloth equivalent blank 22 is positioned above the roof rail inner equivalent blank 21 in the direction of the convexity of the hat shape. By arranging them in this way, cracking can be suppressed by allowing the blank material to flow smoothly during press forming without applying excessive stress to the blank material or welded parts.

[0046] The joining method is not particularly limited. For example, joining can be done by spot welding (resistance spot welding, laser spot welding, etc.), lap welding (arc welding, laser welding), lap fillet welding (arc welding, laser welding), brazing, friction stir welding (FSW), friction pressure welding, etc. Usually, from the standpoint of ease of welding and productivity, it is preferable to join by spot welding. Figure 4 shows an example of a joint 51 in the case of spot welding.

[0047] In conventional methods of connecting the roof rail inner 11 and the roof cloth 12, the roof cloth 12 was welded to the vertical wall portion 112 of the roof rail inner so as to abut against it, resulting in a step at the joint. When the roof panel (automobile ceiling panel) was placed on the roof cloth 12, a gap inevitably formed at this joint, and when the automobile was electrodeposited, paint liquid accumulated in this gap, causing deterioration of the paint quality. In this embodiment, the connection part is integrally press-formed at the overlapping portion, allowing for a smooth connection from the roof cloth 12 to the roof rail inner 11. Since there is no step at the connection part between the roof cloth 12 and the roof rail inner 11, paint liquid does not accumulate. Therefore, according to this embodiment, an improvement in the electrodeposited paint quality of automobiles can also be expected.

[0048] [Bead] By forming a bead at the connection part between the roof rail inner and the roof cross member, the strength and rigidity of the connection part can be enhanced. Here, the bead refers to a convex protrusion (or concave groove) formed by press forming or the like. For example, it is preferable to form a bead extending in the longitudinal direction of the roof cross member on the roof cross member through the overlapping part of the blank corresponding to the roof rail inner and the blank corresponding to the roof cross member. When the roof cross member has a hat-shaped cross section or a C-shaped cross section, it is preferable to form a bead on its top plate part. With this bead, high rigidity can be obtained against the bending moment propagated from the roof cross member, and the impact resistance during vehicle rollover can be improved. Furthermore, by forming the bead, springback after pressing can be suppressed. Whether the bead is convex or concave is not particularly limited, but from the perspective of securing the interior space of the vehicle, it is preferable to make it convex on the outside of the vehicle. The number of beads is not particularly limited. If there is one or more, an effect can be achieved. Fig. 5 shows an example of the bead formed on the roof cross member. Fig. 5(a) shows an overview of the case where two rows of beads 61 are formed. Fig. 5(b) shows its cross-sectional view. Fig. 5(a) is a view seen from the inside of the vehicle, Fig. 5(b) shows a cross section in the longitudinal direction of the roof cross member, the upper part of the drawing is the inside direction of the vehicle, and the lower part is the outside direction of the vehicle. As long as the bead passes through the overlapping part, its length is not limited. The required length can be set according to structural design or the like.

[0049] Figure 6 shows the case where the bead 61 formed on the roof cloth 12, as shown in Figure 5, passes through the roof rail inner 11. By passing the bead 61 through the roof rail inner 11, the rigidity of the roof rail inner 11 can be further increased against bending moments from the roof cloth 12. Figure 6(a) shows an overview of the bead formation in this case, and Figure 6(b) shows a cross-sectional view in the longitudinal direction of the roof cloth. Figure 6(a) is a view from the inside of the vehicle, and Figure 6(b) shows a cross-section in the longitudinal direction of the roof cloth, with the top of the drawing being in the direction of the inside of the vehicle and the bottom being in the direction of the outside of the vehicle. However, when forming a bead that passes through the roof rail inner, depending on the shape of the roof rail inner and the roof cloth, the material flow during press forming becomes complicated, and cracking may occur when the bead is formed. For this reason, it is preferable to determine the bead shape by anticipating the material flow during press forming based on the shape of the roof rail inner and the roof cloth, as well as the shape of the connection part.

[0050] Additionally, beads may be formed on the roof rail inner, extending in the longitudinal direction of the roof rail inner. This compensates for the reduction in strength and rigidity caused by discontinuities (disconnections) in the vertical wall or flange portions of the roof rail inner. In this case, it is preferable to form the beads on the top plate or vertical wall portion of the roof rail inner. In this case as well, there is no particular limit to whether the beads are convex or concave, but from the viewpoint of securing internal space in the vehicle, it is preferable to make them convex toward the outside of the vehicle. There is also no particular limit to the number of beads. One or more beads will be sufficient to achieve the desired effect.

[0051] The roof cloth bead and the roof rail inner bead may be formed in combination. Figure 7 shows a conceptual diagram of this combined case. Figure 7(a) is an external view, and Figure 7(b) shows a longitudinal cross-section of the roof cloth 12. Figure 7(a) is a view from the inside of the vehicle, and Figure 7(b) shows a longitudinal cross-section of the roof cloth, with the top of the drawing being the direction towards the inside of the vehicle and the bottom being the direction towards the outside of the vehicle. The bead 61 of the roof cloth 12 and the bead 61 of the roof rail inner 11 may intersect. However, if the bead 61 of the roof cloth 12 and the bead 61 of the roof rail inner 11 intersect, the material flow behavior during press forming at the intersection becomes complex and may induce cracking of the blank, so it is preferable not to have the two beads intersect. Also, if the beads intersect, discontinuities occur in the walls that make up the bead groove at the intersection of the vertical wall beads, which reduces the effect of the beads in increasing rigidity, so it is undesirable.

[0052] <Method for Manufacturing Roof Frame Components> The method for manufacturing the roof frame components according to this embodiment is not particularly limited. They can be manufactured according to conventional methods. An overview of the manufacturing process in this embodiment is shown in Figure 8, which is the same as general integral press molding using a TWB.

[0053] Blanking Process: This process involves manufacturing blanks that will become the parts of an integrated blank. Blanks are cut from a predetermined steel plate (blanking), and then refined using laser trimming and other methods to produce blanks for each individual part.

[0054] Press-formed integrated blank processing process: This process involves joining multiple blanks to produce a press-formed integrated blank (TWB). In this process, at least one roof cloth-equivalent blank and at least one roof rail inner-equivalent blank are joined at the overlapping portion where they are superimposed on each other. The method of joining the overlapping portion is not particularly limited, but joining by spot welding (resistance spot welding or laser spot welding) is an efficient method. The joining method for the other blanks is not particularly limited. When welding blanks together, laser welding or arc welding can be used. When blanks are superimposed, the joining of the overlapping portion can be done by spot welding (resistance spot welding, laser spot welding, etc.), overlap welding (arc welding, laser welding), overlap fillet welding (arc welding, laser welding), brazing, friction stir welding (FSW), friction pressure welding, etc. An integrated blank (TWB) for press-formed can be obtained by combining and joining predetermined blanks to form an integrated blank.

[0055] In manufacturing the integrated blank, as described above, at least one roof cloth equivalent blank and a roof rail inner equivalent blank are joined together at an overlapping portion where they are superimposed on each other, forming at least one joint. In the roof frame component after integral molding, at least a portion of the overlapping portion is located inside the joint. To achieve this, in manufacturing the integrated blank, at least a portion of the overlapping portion of the blank is located inside the area enclosed by a virtual line indicating the width of the roof rail inner equivalent blank and a virtual line indicating the width of the roof cloth equivalent blank. Preferably, the overlapping portion 41 of the blank is located so as to include an area of ​​50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 100% of the area enclosed by the virtual lines indicating the widths of both blanks.

[0056] The imaginary line 321 indicating the width of the roof rail inner equivalent blank 21 is, as shown in Figure 4(b), a line indicating the outer edge (end face) of the roof rail inner equivalent blank 21 in the direction perpendicular to the longitudinal direction (width direction). The imaginary line 322 indicating the width of the roof cloth equivalent blank 22 is a line drawn perpendicular to the longitudinal direction of the roof rail inner equivalent blank 21 from the intersection point of the outer edge (end face) of the roof cloth equivalent blank 22 in the direction perpendicular to the longitudinal direction (width direction) and the imaginary line 321 indicating the width of the roof rail inner equivalent blank 21.

[0057] Furthermore, when manufacturing integrated blanks for roof frame components, if all blank joints are joined (welded, etc.) before forming, the material flow during press forming is obstructed by the joints, introducing localized deformation. This not only worsens formability but can also cause cracking. Therefore, it is effective to perform joining (welding, etc.) in areas that do not obstruct material flow during press forming, or in areas with little material flow (for example, the blank corresponding to the top plate of the component) (i.e., to position the joints).

[0058] Hot press forming process: This process involves hot press forming the obtained press forming blank (integrated blank). By press forming the press forming blank, a part or a part with a shape close to the part (near-net shape) can be obtained (the part obtained after the hot press process is called a press-formed product). The press forming method is not particularly limited, but generally, when obtaining large-dimensional and high-strength press-formed products (for example, a molded product made from a steel plate with a tensile strength exceeding 590 MPa), hot press forming is preferable from the viewpoint of press load. Hot press forming is also called hot stamping (hot stamping method), and is a press forming method in which the blank (steel plate) is heated to the austenite temperature range of approximately 900°C, and then press-formed while simultaneously rapidly cooling to perform quenching by martensitic transformation. Hot press forming has the characteristics that the press load can be reduced because it is formed at a high temperature, and because martensitic transformation occurs during cooling, it has high strength after forming while having excellent shape retention. For this reason, it is often used when obtaining high-strength press-formed products.

[0059] Trimming Process: This process does not limit the ancillary processes after press forming. Examples include trimming and piercing processes. This process refines the press-formed product (including parts and near-net-shape parts) that has been hot-press-formed. The method of refining the press-formed product is not particularly limited. For example, it includes processes such as laser trimming, which removes burrs and excess material from the edges of the press-formed product to shape it to a predetermined form. In addition, it also includes processes such as piercing, which creates holes to prevent paint or rainwater from accumulating during painting. Furthermore, in the case of near-net-shape press-formed products, it includes processing to create the final part shape. If a press-formed product with the final shape can be obtained through hot-press forming, this trimming process can be omitted.

[0060] Post-pressing parts joining process: In the integrated blank processing process for pressing, any parts that were not joined in the overlapping area because they would hinder material flow during press forming may be joined (e.g., by welding) at this stage. Since the joining is done after press forming, material flow due to press forming has already occurred, so there is no introduction of deformation or cracking due to joining. Therefore, since the parts joined at this stage have not undergone heat treatment by hot pressing, the joined parts will have HAZ softening areas. In other words, in the roof frame parts manufactured by integral press forming of the integrated blank according to this embodiment, at least one of the joints in the overlapping area of ​​the blank (the joint joined before hot stamping) will be a joint without HAZ softening. Then, since the remaining parts are joined after press forming, the roof frame parts according to this embodiment will have both joints without HAZ softening and joints with HAZ softening. Furthermore, if it is necessary to join other parts to the obtained press-formed product, a process for joining them (post-pressing parts joining process) may be provided.

[0061] The joining method here is not particularly limited. For example, joining may be done by spot welding, arc welding, laser welding, brazing, etc. Also, it may be used to attach partial reinforcing materials to press-formed products or to join parts that cannot be formed simultaneously during press forming. Of course, if there is no need to join other parts, this post-press part joining process can be omitted.

[0062] The overlapping portion of the integrated blank, excluding the joint (i.e., the unjoined portion), may be joined after press forming. This is because, having undergone complex material flow, joining (welding) at this stage will not induce cracking.

[0063] By going through these processes, the desired vehicle roof frame component can finally be obtained. However, the manufacturing process for the component by press-forming an integrated blank is not limited to the processes described above. Other necessary processes can be added.

[0064] Conventional designs did not have a component called a roof frame part as in this embodiment. However, after blanking the roof cloth, each piece was press-formed (such as by hot pressing) and trimmed, and then each piece was joined (welded) to the inner roof rail of the door ring during the vehicle assembly process. In other words, a press forming process was required for at least the number of roof cloths. From this alone, it was confirmed from this embodiment that the number of press forming processes can be significantly reduced. Furthermore, with this embodiment, only one part needs to be managed as a roof frame part, whereas in conventional cases, the number of parts needed to be managed for each roof cloth was required. From the perspective of management costs, it was also confirmed from this embodiment that there is a cost reduction effect.

[0065] <Presence or Absence of HAZ Softening Area> Since the roof frame parts obtained from the integrated blank are hot press-formed, the HAZ softening area that occurred before hot press-forming is eliminated by the heat treatment during hot press-forming in the joints formed by welding such as spot welding and lap welding, friction stir welding, and friction pressure welding. In other words, in the parts according to this embodiment, the joints of the overlapping parts of the blank that were joined (welded) before hot press-forming do not have a HAZ softening area. A HAZ softening area is a phenomenon in which the heat-affected zone (HAZ) in the base material just outside the outer edge of the weld metal in spot welding nuggets and arc welding is tempered and becomes softer than the base material. Similarly, in friction stir welding, friction pressure welding, and brazing, the softened area that occurs in the heat-affected zone (HAZ) of the base material just outside the outer edge of the joint is the HAZ softening area. The elimination of the HAZ softening area increases the strength of the joint, thus contributing to the improvement of the impact resistance performance of the finished part. In other words, since at least one of the joints of the roof frame component according to this embodiment does not have a HAZ softening area, the joint is strengthened compared to conventional components (components in which each roof cloth was joined together), and an improvement in the collision resistance performance of the component is expected. The following explanation will use resistance spot welding as an example.

[0066] Figure 9 shows an example of the correspondence between the results of a cross-sectional investigation of a spot-welded test piece 90 and the hardness distribution of the spot weld 91 and the base material 92 (steel plate corresponding to the blank). Unless otherwise specified, hardness refers to Vickers hardness. As can be seen in Figure 9, the spot weld 91 including the nugget 93 has a hardness of about Hv500 because it is hardened (since the hardness is almost the same inside the spot weld, it is good to use the hardness at the center of the spot weld as a representative value). On the other hand, it can be seen that the hardness is softened to about Hv300 at a point about 1 mm away from the edge (outer edge) of the spot weld nugget 93 (near the outer edge of the spot weld). This softened area is the HAZ softening area. Normally, the HAZ softening area occurs in a region within 5 mm of the edge (outer edge) of the nugget or weld metal.

[0067] Further away from the nugget 93, the hardness converges to the hardness of the base material 92 (Figure 9 shows that it converges to a hardness of slightly less than Hv500). The hardness of the HAZ softened area relative to the center of the spot weld 91 is, for example, 50 or more Hv smaller when the base material 92 is a 1.0 GPa grade steel plate, 100 or more Hv smaller when it is a 1.5 GPa grade steel plate, and 150 or more Hv smaller when it is a 2.0 GPa grade steel plate. Generally speaking, if we define Hvm as the hardness of the base material 92, that is, the hardness of the part of the base material 92 unaffected by spot welding, and the maximum value and minimum value among the hardness measured within a range of 5 mm from the end of the nugget outward (towards the base material) as the maximum hardness and the minimum value as the minimum hardness, and the difference between the maximum hardness and the minimum hardness as ΔHv, then in the case where there is no HAZ softening, ΔHv should be 0.2 Hvm or less, preferably 0.1 Hvm or less. Conversely, if the HAZ is softened, ΔHv will exceed 0.2 Hvm.

[0068] The hardness distribution of the HAZ softened area can be determined by measuring the hardness (Vickers hardness) from the center of the spot weld outward along a straight line (hardness measurement line) parallel to the blank surface, at a position 3 / 4 of the way from the blank's surface (i.e., 1 / 4 of the way from the surface of the blank that is in contact with other blanks), in a cross section perpendicular to the surface (thickness direction cross section) that includes the center of the joint (center of the spot weld) on the surface of the outermost blank among the blanks. It is preferable to measure the hardness distribution in the thickness direction cross section of the outermost blank among the blanks that make up the overlapping section. First, as the base material hardness (hardness of the base material in a part unaffected by spot welding), measure the hardness at a position 15 mm or more away from the center of the spot weld and where no spot welding has occurred, and define that hardness as Hvm. Specifically, along the hardness measurement line, the hardness is measured at 10 arbitrary points selected within a range of 15 mm to 25 mm from the center of the spot weld, where no spot welding has been performed, with a measurement interval (pitch) of 0.15 mm or more. The arithmetic mean of these 10 measurements is taken as the base material hardness Hvm. Note that the outermost blank here refers to the blank on the top surface when the press-formed part is placed with the convex shape facing upwards.

[0069] Next, the hardness is measured along the hardness measurement line, in a range of 5.0 mm from the outer edge (end) of the weld metal (nugget) outward (towards the base metal) at measurement intervals (pitch) of 0.15 to 0.25 mm. The maximum value of the measured hardness is taken as the maximum hardness, and the minimum value as the minimum hardness, allowing the difference ΔHv between the maximum and minimum hardness to be determined. This is because within this range, the minimum hardness of the HAZ softened area due to spot welding can be captured. The outer edge of the weld metal (such as the outer edge of the spot weld) can be identified as the boundary between the spot weld and the base metal by the contrast created by etching the Vickers hardness measurement sample.

[0070] Vickers hardness is measured on a sample with the measurement plane containing the center of the weld metal (center of the spot weld) at x, in accordance with JIS Z 2244-1:2024, with a test force of 300 gf (2.942 N) and a holding time of 10 seconds.

[0071] Joints that do not have a HAZ softened area (spot-welded joints in the above description) are formed before hot press forming. That is, in the roof frame component according to this embodiment, at least one joint (spot-welded in the above description) in the overlapping area of ​​the roof cloth equivalent blank and the roof rail inner equivalent blank is a joint that does not have a HAZ softened area, meaning that the difference ΔHv between the maximum hardness and minimum hardness near the end of the joint is 0.2 times or less the hardness of the base material (0.2 Hvm or less).

[0072] The hardness measurement of the HAZ softened area was explained using resistance spot welding as an example. For other joining methods, the same considerations apply as to resistance spot welding. For arc welding, the same applies as to resistance spot welding. For laser welding, the "weld metal" should be replaced with the molten metal portion, and for FSW and friction welding, the "weld metal" should be replaced with the agitated portion. For brazing, the "weld metal" should be replaced with the portion directly above the blank surface perpendicular to the brazed area. Furthermore, regarding the hardness measurement line, if the shape of the joint on the blank surface is point-shaped, such as in laser spot welding, the hardness should be measured by assuming a hardness measurement line, similar to resistance spot welding. If the shape of the joint on the blank surface is linear, such as in linear lap fillet welds or linear FSW, the hardness should be measured by assuming a hardness measurement line by replacing the cross section perpendicular to the joint line (weld line, etc.) with the "thickness direction cross section".

[0073] This embodiment has been described through the examples above. As mentioned above, according to this embodiment, the number of press molding processes can be significantly reduced from the standpoint of production technology compared to the conventional method, and from the standpoint of parts management, the management burden is also significantly reduced because it only requires managing one part as a roof frame component, instead of managing each type of roof cloth as in the conventional method.

[0074] This invention can be widely used in a wide range of industrial fields, including the transportation machinery industry (such as automobiles), the general machinery industry, and electrical equipment.

[0075] 100 Vehicle frame (automobile frame) 101 Roof frame parts 11 Roof rail inner 111 Roof rail inner top plate section 112 Roof rail inner vertical wall section 113 Roof rail inner flange section 12 Roof cloth 121 Roof cloth top plate section 122 Roof cloth vertical wall section 123 Roof cloth flange section 201 Integrated blank 21 Blank equivalent to roof rail inner 211 Blank equivalent to roof rail inner top plate section 212 Blank equivalent to roof rail inner vertical wall section 213 Blank equivalent to roof rail inner flange section 22 Blank equivalent to roof cloth 221 Blank equivalent to roof cloth top plate section 222 Blank equivalent to roof cloth vertical wall section 223 Blank equivalent to roof cloth flange section 311 Imaginary line indicating the width of the roof rail inner 312 Imaginary line indicating the width of the roof cloth 321 Imaginary line indicating the width of the blank equivalent to the roof rail inner 322 Imaginary line indicating the width of the blank equivalent to the roof cloth 31 Connection part 41 Overlap part 51 Joint part 61 Bead 90 Spot weld test piece 91 Spot weld part 92 Base material (blank) 93 Nugget

Claims

A vehicle roof frame component that forms the roof portion of a vehicle and is made up of multiple steel plates joined together, The aforementioned roof frame component is It has two inner roof rails that extend in the direction of vehicle travel. It has one or more roof crosses connected to the two roof rail inners, The blank corresponding to the roof rail inner and the blank corresponding to the roof cloth have a joint where they are joined at the overlapping portion where they are superimposed on each other. A vehicle roof frame component characterized by the following features. 　 The vehicle roof frame component according to claim 1, wherein the joint portion is located in the overlapping portion of the connection portion where at least one roof rail inner and at least one roof cross are connected. 　 The roof cloth comprises a top plate portion extending in the longitudinal direction of the roof cloth and at least one vertical wall portion adjacent to the top plate portion. The roof rail inner comprises a top plate portion extending in the longitudinal direction of the roof rail inner and at least one vertical wall portion adjacent to the top plate portion. The vehicle roof frame component according to claim 1 or 2, wherein the connecting portion is connected such that the roof cross abuts against the vertical wall portion of the roof rail inner. 　 The overlapping portion is provided at least on the top plate portion of the roof rail inner, as described in claim 3 for a vehicle roof frame component. 　 A vehicle roof frame component according to any one of claims 1 to 4, wherein the roof cloth has a bead that passes through the overlapping portion and extends in the longitudinal direction of the roof cloth. 　 The roof frame component for a vehicle according to any one of claims 1 to 5, wherein the roof rail inner has a bead that passes through the overlapping portion and extends in the longitudinal direction of the roof rail inner. 　 The roof frame component for a vehicle according to any one of claims 1 to 6, wherein the roof frame component is a hot-stamped component. 　 The vehicle roof frame component according to any one of claims 1 to 7, wherein at least one of the aforementioned joints is a joint without a HAZ softening portion. 　 In the joint portion where the HAZ softening portion is absent, in a cross-section perpendicular to the surface of the outermost blank including the center of the joint portion, at a position 3 / 4 of the plate thickness from the surface of the outermost blank, When the Vickers hardness at a position 15 mm or more away from the center of the joint and not joined is Hvm, The vehicle roof frame component according to claim 8, wherein the difference between the maximum and minimum hardness in Vickers hardness, ΔHv, in a range of 5 mm or less from the end of the weld metal of the joint toward the base material is 0.2 Hvm or less. 　 The roof cloth comprises a top plate portion extending in the longitudinal direction of the roof cloth and at least one vertical wall portion adjacent to the top plate portion. The roof rail inner comprises a top plate portion extending in the longitudinal direction of the roof rail inner and at least one vertical wall portion adjacent to the top plate portion. The vehicle roof frame component according to claim 8 or 9, wherein the joint portion without the HAZ softening portion is present in one or both of the top plate portion of the roof rail inner and the top plate portion of the roof cloth. 　 A press-formed integrated blank configured as a joint structure for multiple steel plates for a vehicle roof frame component that constitutes the roof of a vehicle, The aforementioned roof frame component is It has two inner roof rails that extend in the direction of vehicle travel. It has one or more roof crosses connected to the two roof rail inners, The aforementioned integrated blank is It has two blanks corresponding to the roof rail inner that extend in the direction of vehicle travel, It has one or more blanks corresponding to a roof cross that are connected to the two blanks corresponding to roof rail inners, An integrated blank for a vehicle roof frame component, characterized in that at least one blank corresponding to the roof rail inner and at least one blank corresponding to the roof cloth have a joint portion joined at an overlapping portion where they are superimposed on each other. 　 The blank corresponding to the roof cloth comprises a top plate portion extending in the longitudinal direction of the blank corresponding to the roof cloth and at least one vertical wall portion adjacent to the top plate portion. The blank corresponding to the roof rail inner comprises a top plate portion extending in the longitudinal direction of the blank corresponding to the roof rail inner and at least one vertical wall portion adjacent to the top plate portion. The integrated blank for a vehicle roof frame component according to claim 11, wherein the overlapping portion is arranged in at least the portion corresponding to the top plate portion of the blank corresponding to the roof rail inner. 　 The integrated blank for a vehicle roof frame component according to claim 11 or 12, wherein the joint is a joint formed by resistance spot welding, laser spot welding, or overlap welding. 　 The joint portion is located in at least one of the portion corresponding to the top plate portion of the blank corresponding to the roof rail inner and the portion corresponding to the top plate portion of the blank corresponding to the roof cloth. An integrated blank for a vehicle roof frame component according to any one of claims 11 to 13.

Images